feat(LSP): Add support for autoformatting in C#

Make the omnisharp language server format C# files on write.

after/plugin/LSP.lua

@@ -22,6 +22,25 @@ modules["mason-lspconfig"].setup_handlers {
 		modules["lspconfig"][server_name].setup {
 			capabilities = capabilities
 		}
+	end,
+	["omnisharp"] = function ()
+		modules["lspconfig"]["omnisharp"].setup {
+			capabilities = capabilities,
+			on_attach = function (client,buffnr)
+				vim.notify("attaching to CS buffer {" .. buffnr .. "}")
+				local gr = vim.api.nvim_create_augroup("CS-OnAttach",{})
+				vim.api.nvim_create_autocmd({"BufWritePre"}, {
+					group = gr,
+					pattern = {"*.cs"},
+					desc = "(C#) Format before write",
+					callback = function ()
+						vim.lsp.buf.format()
+					end
+				}
+				)
+				vim.notify("Attached to CS buffer")
+			end
+		}
 	end
 }